1. Field of the Invention
The invention is related to a polar transmitter, and particularly to a phase modulator in the polar transmitter and a phase modulation method implemented therein.
2. Description of the Related Art
A polar structure radio frequency (RF) transmitter is a highly developed technology for and a core technology of telecommunication systems. The polar structure radio frequency (RF) transmitter assists power amplifiers to exhibit better performance. In the polar structure, original inphase/quadrature (I/Q) signals are polarized into a pair of magnitude signals and phase signals. Theoretically, significant bandwidths are required to render amplitude and phase signals without degrading the original signal quality. The bandwidth, however, is physically limited, thus undesirable error vector magnitude (EVM) and spectral regrowth problems are induced. It is therefore desirable to develop a simple and cost effective approach to increase the utilization of bandwidths for polar structure radio frequency (RF) transmitters.